In today's world, the energy crisis has received a growing concern from people all over the world. Conventional automobiles rely on non-renewable energy, such as gasoline, diesel and so on. At present, reserves of this kind of energy on earth have continuously decreased. More and more wars break out due to the energy crisis. The emergence of new energy automobile can effectively alleviate the energy crisis and achieve the sustainable development. Moreover, the environmental pollution has become an increasingly serious problem. The combustion of gasoline or diesel produces a large quantity of sulfide or particulate matter. These products will seriously pollute the atmosphere, and even worse, when encountering rain, the sulfide is easy to form acid rain, which will bring other pollution problems. As series of problems arise, there is an urgent demand on new energy industry and new energy automobile. At the same time, in order to vigorously promote the development of new energy automobiles, the government has introduced a series of high subsidy policies. These policies have played a positive role in the development of new energy automobiles, but also put forward higher and higher requirements on the new energy automobile technology. Especially the safety performance of the new energy automobile has always been the focus of people's attention. A relay serves as an element in a battery management system for controlling open and close each branches. When an open-circuit fault occurs in the relay, the fault will directly affect some functions to be unavailable to use. When an adhesion fault occurs in the relay, the relay cannot be opened such that a series of serious problems, such as overcharge, over discharge, over-temperature, etc. will be likely to arise. Therefore, it is important to accurately diagnose if there is an open-circuit or adhesion fault occurs in a high-voltage relay.
One of the disclosed methods for relay diagnosis is mainly used to detect the relay circuit. However, considering the relay circuit per se has other devices, this method has such a drawback that in case of the occurrence of faults in the other devices, the method is unable to diagnose the relay.